Lever operated electrical switches

ABSTRACT

A lever operated microswitch comprises a switch mechanism actuated via plunger slidably mounted in an opening in the switch casing housing the mechanism, and a lever mounted externally on the casing and arranged to bear on the projecting end of the plunger. The lever may be entirely moulded from resilient plastics material and be fixed to the switch casing by a boss at one end engaged in a cooperating groove in the casing. Alternatively, the lever may comprise a lever arm formed from metal strip attached to a hinge piece moulded from resilient plastics material, this hinge piece being fixed to the switch casing by a boss at its free end engaged in a cooperating groove in the casing. In either event, the plastics part is flexible and permits the lever to be rocked so as to depress the plunger and actuate the switch mechanism.

United States Patent 1.

Beer

[ Nov. 20, 1973 LEVER OPERATED ELECTRICAL SWITCHES [73] Assignee: OtehallLimited,Burgess Hill,

Sussex, England 22 Filed: Sept. 1, 1972 [21 I Appl. No.: 285,584

Primary ExaminerRobert K Schaefer Assistant ExaminerWilliam J. Smith AttorneyJ0seph F. Brisebois et al.

[ 5 7 1 ABSTRACT A lever operated microswitch comprises a switch mechanism actuated via plunger slidably mounted in an opening in the switch casing housing the mechanism, and a lever mounted externally on the casing and arranged to bear on the projecting end of the plunger. The lever may be entirely moulded from resilient plastics material and be fixed to the switch casing by a boss at one end engaged in a cooperating groove in the casing. Alternatively, the lever may comprise a lever arm formed from metal strip attachedto a hinge piece moulded from resilient plastics material, this hinge piece being fixed to the switch casing by a boss at its free end engaged in a cooperating groove in the casing. in either event, the plastics part is flexible and permits the lever to be rocked so as to depress the plunger and actuate the switch mechamsm.

9 Claims, 9 Drawing Figures PATENTEB NOV 20 I975 SHEET 1 BF 2 LEVER OPERATED ELECTRICAL SWITCHES The present invention relates to electrical switches, and more particularly, microswitches, of the type in which the switch movement or mechanism is actuated by a plunger slidably mounted in an opening in the switch casing housing the mechanism. Depression of the plunger actuates the switch mechanism which moves a contact-carrying member of the mechanism from one position to another.

It is often required to actuate such switches by means of a lever. In one conventional arrangement for lever operation, the lever is externally pivoted to the switch casing at a position spaced from the plunger and is arranged to bear on the projecting end of the plunger. The lever can then be rocked about its pivot to depress the plunger.

It is an object of the present invention to provide a simple form of lever and leverhinge for a leveroperated switch of the type referred to above. To this end, according to the invention, a lever device, which is disposed externally of the switch casing and is arranged to bear on the projecting end of the plunger, has one end fixed to the switch casing by an interengaging boss and groove arrangement, at least said fixed end and the adjacent portion of the lever being formed from resilient material so that the lever is flexible and can be rocked to depress the plunger and actuate the switch mechanism. Preferably, the fixing boss is disposed on the lever device and its cooperating groove is formed in the switch casing.

The lever device may be entirely moulded from resilient plastics material. Alternatively, it may comprise a lever arm, preferably formed from metal strip, which is arranged 'to bear on the plunger, and a hinge piece moulded from resilient plastics materials, said hinge piece having one end fixed to the switch casing by the interengaging boss and groove arrangement and having a connector part formed with means connecting the lever arm to the hinge piece, and said hinge piece being flexible and permitting the lever arm to be rocked so as to depress the plunger.

The lever device according to the invention eliminates all moving joints or hinges between separate parts and thus eliminates or reduces side play, loss of movement through mechanical hinges, and general slackness in the lever mechanism. It provides an accuracy in operation which has hitherto only been achieved with complicated, multi-component lever mechanisms. The plastics hinge piece readily permits the use of strip leopening for the actuating plunger, and a side plate which is secured to the body part over the cavity and the slot for closing the adjacent open sides thereof and retaining the mechanism and plunger in position. The.

two parts are secured together by adhesive,.welding or riveting after the switch mechanism etc., has been assembled in the body part.

With this construction of casing, it has been found that the opening or slot in which the plunger is slidably mounted tends to deform and vary in width owing to shrinkage or warpage of the plastics mouldings caused by varying atmospheric conditions, such as varying conditions of temperature and humidity. This can result in the plunger opening narrowing to such an extent that the plunger becomes jammed in the opening.

It is therefore another object of the present invention to prevent such an eventuality and, to this end, the invention also consists in an electrical switch casing of the above described construction, in which the casing is of a rectangular shape corresponding to the required width of the plunger opening.

The plunger opening may have part cylindrical recesses formed in opposite sides thereof for pivotally mounting the cylindrical boss portion of a rockable actuating member, which can be mounted in the slot in the place of the plunger as described in US. Pat. No. 3,604,879. In this event, the boss portion on the side plate prevents the slot from narrowing and causing the cylindrical boss portion of the rockable actuating member binding in the mounting recesses.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings in which:

FIG. 1 illustrates a side elevation, with the side plate 7 partially broken away, of a microswitch embodying the vers of different lengths and/or having different follower devices on their free ends, and enables the levers to be changed to suit different purposes. Moreover, it readily permits the specified electrical tracking and clearance distances to be achieved between the switch mechanism and the ground operating lever.

In a modification, the plastics lever or the plastics part of this lever may be moulded integrally with the switch casing. Such a lever may have a web of reduced thickness serving as a hinge or may be simply flexible to depress the plunger.

In a plunger-operated switch of the type referred to above, the insulating casing housing the switch mechanism is normally moulded in two parts from plastics material, that is a body part, which has a cavity moulded in one side for containing the switch mechanism and a slot moulded in the same side defining the invention,

FIG. 2 is a fragmentary perspective view of the switch shown in FIG. 1, I

FIG. 3 is a fragmentary perspective view of the inside of the side plate of the switch shown in FIG. 1,

FIG. 4 is a fragmentary side view of a microswitch with the side plate partially broken away, illustrating another embodiment of the invention,

FIG. 5 is a fragmentary, underneath perspective view form of-hinge piece and lever arm.

Referring to FIGS. 1, 2 and 3, the microswitch has an insulating casing comprising a body part I and a side plate 2, both formed as plastics mouldings. The body part 1 is moulded with a cavity 3 for containing the switch mechanism 4, with slots in its peripheral wall for mounting the terminals 5, and with fixing holes 6. It

also has a slot or opening 7 in which is slidably mounted a plunger 8 for operating the switch mechanism 4. 9 are part-cylindrical recesses for mounting a rockable actuating member in place of the plunger, as described in the aforementioned patent. The side plate 2 is secured over the cavity side of the body part, after assembly of the switch mechanism, terminals and plunger, in order to enclose these and retain them in position. Moulded on the inside surface of the side plate opposite the open side of the plunger slot 7 is a shallow rectangular boss portion 10 of width and height dimensions substantially equal to the width and height of the plunger slot. When the slide plate is secured to the body part, the boss portion fits into the open side of the plunger slot, as shown in FIG. 2, and serves as a spacer which restricts deformation and narrowing of the slot, owing to shrinkage or warpage of the plastics casing caused by variations in ambient atmospheric conditions, and prevents consequent jamming of the plunger in its slot.

The switch mechanism 4, only a part of which is shown in FIG. 1, may be of any convenient construction and comprises a movable contact-carrying member which is spring biased into one position. The plunger 8 bears on a member of the mechanism and, upon depression of the plunger the contact-carrying member snaps over from said one position to another. It snaps back to its initial position upon release of the plunger.

The plunger 8 is operated via a lever device 11 which bears on the projecting end of the plunger. The lever is moulded from a resilient plastics material for example, nylon, and is of generally strip-like form. Moulded integrally with one end of the lever is a generally cylindrical boss 12 which is an interference fit in a correspondingly shaped groove 13 formed in the same wall of the casing part 1 as the plunger slot 7, but spaced from the latter. The lever is formed with a bend adjacent its boss so that when the latter is engaged in the groove, the lever projects over the end of the plunger. The groove 13 is formed into the casing wall from the open side of part 1 and does not extend for the full width of the part. Upon assembly of the switch, the boss 12 is slid into the groove through the open end thereof prior to fixing of the side plate 2 which also closes the open end of the groove. The side plate 2 includes a cylindrical boss portion 13a which fits into the open end of the groove 13 so as to centralise the lever with respect to the projecting end of the plunger.

The lever 11 can be flexed downwardly so as to depress the plunger and actuate the switch mechanism. Upon release of the lever, it returns to its rest position owing to its own inherent resilience assisted, if necessary, by the spring return of the switch mechanism raising the plunger.

FIG. 4 illustrates another embodiment of lever device I for a microswitch. The microswitch illustrated is similar to that shown in FIG. 1 and like reference numerals indicate similar parts. The lever is a composite lever and comprises a plastics hinge piece 14 and a strip-metal lever arm 15 bearing on the plunger 8. The hinge piece is moulded from resilient plastics material such as nylon, and includes a generally cylindrical boss portion 16 at the lower end of an upstanding portion 17, these portions being an interference fit in a generally cylindrical groove 18, formed in the wall of the body part 1 at a position spaced from the plunger. The groove 18 is formed into the casing wall from the open side of the part 1 and does not extend through the full width of the the same manner as the previous embodiment. The upstanding portion 17 is integral with a connector part in the form of a strip portion 19 projecting towards the plunger and is connected to the strip portion 19 by a web 20 of reduced thickness which serves as a hinge for the lever device. The metal lever arm 15 is connected to the upper face of the strip portion 19' by studs 21 moulded integrally with 19 and projecting through apertures 22 in the arm. The studs are moulded with heads 23 which engage the face of the arm 15 remote from the strip portion 19 to fasten the arm and hinge piece together. The arm 15 is secured to the hinge piece 14 by inserting the arm into a suitably constructed mould and moulding the hinge piece with the headed studs projecting through the preformed apertures 22 in the arm.

In order to actuate the switch, the lever can be rocked downwardly about its web hinge 20 to depress the plunger. Upon release of the lever, it is returned to its initial position by the resiliency of the hinge and the spring return of the switch mechanism acting through the plunger.

FIG. 5 illustrates a composite lever similar to that shown in FIG. 4, but having a modified form of connection between the lever arm 15 and the plastics hinge piece 14. Thus, the plastics hinge piece 14 has a strip portion 24 of similar cross-section to the strip-metal lever arm and projecting approximately at right angles to the integral web hinge 20. The arm 15 is connected to the hinge piece, flush with the strip portion 24, by a connector plate 26 moulded integrally with the strip portion 24 and having two integrally moulded studs 27 projecting through apertures in the arm 15. The plate 26 is of lesser width than the lever arm and this has the advantage of avoiding undesirable moulding flashes projecting from the sides of the lever device when the hinge piece is moulded on the preformed lever arm.

Referring to FIGS. 6, 7 and 8, this lever-operated microswitch has an insulating casing and switch mechanism similar to those of the previous embodiments. Its plunger 8 is actuated via a lever device 28 having a lever arm 29 which bears on the projecting end of the plunger. The lever arm is made from metal strip and is hinged to body part 1 by a plastic hinge piece 30 which may, for example, be moulded from nylon. The hinge piece comprises an upstanding part 31 securing the hinge piece to the switch casing and a connector part 32 connecting the strip metal lever arm to the hinge piece. The part 31 has a boss 31a of generally cylindrical shape and is an interference fit in a groove 33 of corresponding shape formed in the wall of the body part 1 containing the plunger slot or opening 7 at a position spaced from the plunger. The groove 33 isside surface for centralising the lever device relative to the plunger.

The connector part 32 is arranged to project from the upper end of the part 31 towards the plunger and is connected to the part 31 via a web 34 of reduced thickness which serves as a hinge. The connector part is in the form of a socket open at opposite ends and its hollow interior is of a generally rectangular cross-section corresponding to the cross-section of the lever arm. It has mutually parallel side walls 35 and top and bottom boundaries defined by spaced transverse webs 36, 37 interconnecting the side walls 35. The two top webs 36 are disposed opposite the spaces 38 between the three bottom webs 37, the central one of which is disposed opposite the space 39 in the top. The ends of the side walls are inclined downwardly from the top webs. The hinge web 34 is integral with the rear bottom web 37.

The lever is slidable longitudinally into the socket connector 32 through the front or free end thereof and is an interference fit in this connector. The bottom web 37 at the free end of the connector is inclined slightly upwards so that it exerts a wedging action on the lever as it is pushed into the connector. The lever is positioned in the connector part so that its leading end projects over the upstanding part 31 and can engage the switch casing in the rest position of the switch. This provides a degree of protection against excessive flexing of the hinge if an upward force is accidentallly or inadvertently applied to the actuating end of the lever arm 29. In order to actuate the switch the lever arm 29 can be rocked downwardly about the web hinge 34 to depress the plunger. Upon release of the lever, it is returned to the rest position by the spring return of the plunger and the inherent resiliency of the hinge piece 30. It will be apparent that the lever arm 29 can readily be changed by manually withdrawing it from the connector 32 and sliding in another lever.

In order to provide for more positive retention of the lever arm 29 within the socket connector, the lever arm is formed with a dimple 40 in its upper surface which snaps into engagement with the top webs 36 of the socket connector when the lever arm is inserted into the connector (FIG. 6). An alternative arrangement for more positively retaining the lever arm in the socket connector is illustrated in FIG. 9. In this arrangement, the lever arm has two lugs 41 formed upwardly therefrom and spaced apart by a distance substantially equal to the width of a top web 36 of the connector. Thus, when the lever arm is inserted into the socket connector, the front top web snaps into engagement with the lugs, as shown, to prevent ready removal of the lever arm. FIG. 9 also illustrates a modified hinge piece 30 in which there is no web hinge 34 of reduced thickness. The socket connector 32 is simply formed integrally with the upstanding part 31 via an extension 42 of the rear bottom web 37 and the lever arm rocks about this extension upon actuation of the lever.

Whilst particular embodiments have been described, it will be understood that various modifications can be made without departing from the scope of the invention as defined by the appended claims.

I claim:

1. In an electrical switch comprising a switch mechanism housed within an insulating switch casing, a plunger for actuating said switch mechanism slidably supported in an opening in a top wall of said switch casing, and separate lever means for depressing the plunger and actuating said mechanism disposed externally of said casing, said lever means being connected to the top wall of the casing at a position spaced from the plunger and extending over the plunger to bear on the projecting end thereof, the improvement consisting in that said lever means is rigidly fixed to the switch casing by a boss which is formed at the end of a portion of the lever means projecting downwardly from the main body thereof, and which is engaged in a complementary groove formed in said top wall of said casing, said downwardly projecting portion at at least an adjacent portion of the main body of said lever means being formed from resilient plastics material to permit the lever means to be flexed relative to said boss and depress the plunger.

2. An electrical switch as claimed in claim 1, in which said downwardly projecting portion and said adjacent portion of the main body of said lever means constitute a hinge piece formed as a one-piece moulding of resilient plastics material, and said adjacent portion includes a connector part formed with means connecting a strip metal lever arm to said hinge piece, said lever arm extending from said hinge piece over said plunger to bear on the projecting end thereof.

3. An electrical switch as claimed in claim 2, in which said connector part of said hinge piece comprises at least one stud moulded integrally therewith, said stud projecting through an aperture in said lever arm and being moulded with a head engaging the face of said lever arm opposite that engaging said connector part, whereby to fix said lever arm to said hinge piece.

4. An electrical switch as claimed in claim 3, in which said connector part comprises a projecting plate portion to which said lever arm is fixed by said at least one stud, said plate portion being of less width than said lever arm.

5. An electrical switch as claimed in claim 2, in which said connector part is in the form of a socket, and said lever arm is longitudinally insertable into said socket and is an interference fit therein, whereby to attach said lever arm to said hinge piece.

6. An electrical switch as claimed in claim 5, in which said socket connector is of generally rectangular crosssection corresponding to the cross-section of said strip lever arm and is open at opposite ends, said socket comprising side walls substantially parallel to the longitudinal edges of said lever arm and top and bottom sides defined by spaced transverse webs at said top side of said socket being disposed opposite spaces between said bottom webs, and in which one said webs at the free end of said socket connector is slightly inclined inwardly of said socket to effect a wedging action on said lever arm, and said lever arm has means which engages in said transverse webs when said lever arm is inserted into said socket so as positively to locate said lever arm in position.

7. An electrical switch as claimed in claim 6, in which said downwardly projecting portion and boss are disposed at one end of said hinge piece and said socketconnector projects from said downwardly projecting portion towards the plunger, and in which the end of said lever arm remote from said plunger extends through said socket and is engageable with the top wall of the switch casing on the opposite side of the hinge body part, which has a cavity in one side for containing said switch mechanism and a slot in its top wall at said one side defining said plunger opening, and a side plate secured to said body part over said cavity and slot for closing the adjacent open sides thereof, and in which said groove is formed in said top wall of said body part at a position spaced from said plunger slot with an open end at said cavity side of said body part, which open end is also closed by said side plate, said boss of said lever means being slidable into said groove through I said open end thereof prior to securing of said side plate, and in which said side plate comprises a first, sizing boss moulded on its insidesurface opposite said plunger slot, the width of said sizing boss corresponding to the required width of said plunger slot, and said sizing boss fitting into said open side of said plunger slot, when said side plate is secured to said body part, and serving as a spacer, and a second boss moulded on the inside surface of said side plate opposite said open end of said groove, said second boss fitting into said open end of said groove, when said side plate is secured in position, to centralise said lever means with respect to said plunger.

9. In an electrical switch, an insulating switch casing comprising a body part and a side plate, a switch mechanism housed within said switch casing, and a plunger for actuating said switch mechanism, slidably mounted in an opening in said casing, said body part having a cavity in one side thereof for containing said switch mechanism and at least a slot in the same side thereof defining said plunger opening, said side plate being secured to said body part over said cavity and said slot for closing the adjacent open sides thereof, said side plate having a sizing boss moulded on its inside surface opposite said plunger slot, the width of said boss corresponding to the required width of said plunger slot, and said boss fitting into said open side of said plunger slot, when said side plate is secured to said body part, and serving as a spacer to prevent undesirable narrowing of said slot. 

1. In an electrical switch comprising a switch mechanism housed within an insulating switch casing, a plunger for actuating said switch mechanism slidably supported in an opening in a top wall of said switch casing, and separate lever means for depressing the plunger and actuating said mechanism disposed externally of said casing, said lever means being connected to the top wall of the casing at a position spaced from the plunger and extending over the plunger to bear on the projecting end thereof, the improvement consisting in that said lever means is rigidly fixed to the switch casing by a boss which is formed at the end of a portion of the lever means projecting downwardly from the main body thereof, and which is engaged in a complementary groove formed in said top wall of said casing, said downwardly projecting portion at at least an adjacent portion of the main body of said lever means being formed from resilient plastics material to permit the lever means to be flexed relative to said boss and depress the plunger.
 2. An electrical switch as claimed in claim 1, in which said downwardly projecting portion and said adjacent portion of the main body of said lever means constitute a hinge piece formed as a one-piece moulding of resilient plastics material, and said adjacent portion includes a connector part formed with means connecting a strip metal lever arm to said hinge piece, said lever arm extending from said hinge piece over said plunger to bear on the projecting end thereof.
 3. An electrical switch as claimed in claim 2, in which said connector part of said hinge piece comprises at least one stud moulded integrally therewith, said stud projecting through an aperture in said lever arm and being moulded with a head engaging the face of said lever arM opposite that engaging said connector part, whereby to fix said lever arm to said hinge piece.
 4. An electrical switch as claimed in claim 3, in which said connector part comprises a projecting plate portion to which said lever arm is fixed by said at least one stud, said plate portion being of less width than said lever arm.
 5. An electrical switch as claimed in claim 2, in which said connector part is in the form of a socket, and said lever arm is longitudinally insertable into said socket and is an interference fit therein, whereby to attach said lever arm to said hinge piece.
 6. An electrical switch as claimed in claim 5, in which said socket connector is of generally rectangular cross-section corresponding to the cross-section of said strip lever arm and is open at opposite ends, said socket comprising side walls substantially parallel to the longitudinal edges of said lever arm and top and bottom sides defined by spaced transverse webs at said top side of said socket being disposed opposite spaces between said bottom webs, and in which one said webs at the free end of said socket connector is slightly inclined inwardly of said socket to effect a wedging action on said lever arm, and said lever arm has means which engages in said transverse webs when said lever arm is inserted into said socket so as positively to locate said lever arm in position.
 7. An electrical switch as claimed in claim 6, in which said downwardly projecting portion and boss are disposed at one end of said hinge piece and said socket connector projects from said downwardly projecting portion towards the plunger, and in which the end of said lever arm remote from said plunger extends through said socket and is engageable with the top wall of the switch casing on the opposite side of the hinge piece to the plunger and serves as a stop limiting movement of said lever means in the upward direction of said plunger, said socket connector being integral with said downwardly projecting portion via a web portion of reduced thickness which serves as a hinge about which said lever means is rockable.
 8. An electrical switch as claimed in claim 1, in which said switch casing is formed in two parts comprising a body part, which has a cavity in one side for containing said switch mechanism and a slot in its top wall at said one side defining said plunger opening, and a side plate secured to said body part over said cavity and slot for closing the adjacent open sides thereof, and in which said groove is formed in said top wall of said body part at a position spaced from said plunger slot with an open end at said cavity side of said body part, which open end is also closed by said side plate, said boss of said lever means being slidable into said groove through said open end thereof prior to securing of said side plate, and in which said side plate comprises a first, sizing boss moulded on its inside surface opposite said plunger slot, the width of said sizing boss corresponding to the required width of said plunger slot, and said sizing boss fitting into said open side of said plunger slot, when said side plate is secured to said body part, and serving as a spacer, and a second boss moulded on the inside surface of said side plate opposite said open end of said groove, said second boss fitting into said open end of said groove, when said side plate is secured in position, to centralise said lever means with respect to said plunger.
 9. In an electrical switch, an insulating switch casing comprising a body part and a side plate, a switch mechanism housed within said switch casing, and a plunger for actuating said switch mechanism, slidably mounted in an opening in said casing, said body part having a cavity in one side thereof for containing said switch mechanism and at least a slot in the same side thereof defining said plunger opening, said side plate being secured to said body part over said cavity and said slot for closing the adjacent open sides thereof, said side plate having a sizing boss mOulded on its inside surface opposite said plunger slot, the width of said boss corresponding to the required width of said plunger slot, and said boss fitting into said open side of said plunger slot, when said side plate is secured to said body part, and serving as a spacer to prevent undesirable narrowing of said slot. 